Telephone-transmitter



(No Model.)

G. M. HOPKINS. Telephone Transmitter.

No. 231,226. Patented Aug. 17,1880.

wmesses; i 1 NTOR: gmwm Zw flz dwalm,

NFEIES, PHOTQ-LITROGRAPHER, WASHINGTON, D c

NITED STATES PATENT OFFICE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 231,226, dated August17, 1880.

Application filed April 26, 1880.

To all whom it may concern:

Be it known that I, GEORGE M. HOPKINS, of Brooklyn, in the county ofKings and State of New York, have invented a new and usefulTelephone-Transmitter; and I do hereby declare that the following is afull, clear, and eX- act description thereof, reference being had to theaccompanying drawings, which are a part of this specification.

Figure 1 is a vertical section of the transmitter, showing the relationof the several parts. Fig. 2 is a detail view of a modified form ofcontact point attached to the diaphragm. Fig. 3 is a'sectional view ofatransmitter employing a lever to move the contactsurface.

My invention relates to instruments for transmitting articulate speech,musical sounds, signals, and all kinds of sounds that can be made toproduce vibratory motion in diaphragms, reeds, or other vibratory bodiesby the agency of an electric current.

The invention consists, essentially, in a contact-surface attached to avibratory diaphragm and a floating electrode pressed against thecontact-surface by a column of liquid.

The hollow standard A is secured to a fixed support, B, and has formedon its upper end a support for the diaphragm O, which is clamped in itsplace by the cap D. To the center of the diaphragm is attached'a smallmetallic cup, E, which contains a button, F, of ordinary battery-carbon.

The diaphragm C may be of metal or mica. If of metal the diaphragm ismade part of the electrical conductor, the circuit being completed.-through the spring G, attached to the diaphragm-support and connectingwith the wire H, running downward through the hollow standard A and itssupport. I

In the standard A there is a ring, I, having a stud, a, that projectsthrough a slot in the side of the standard, and is provided with amilled nut, by which it may be fixed in any desired position.

A bottle, K, having a long narrow neck, L, and a rounded base rests onthe ring I, and may be supported at any desired height in the hollowstandard A. A platinum wire enters the lower end of the bottle, and isconnected with a coiled wire, M, the end of which ex tends through thebase of the instrument.

(No model.)

The bottle K is partly filled with mercury, which comes into contactwith the platinum wire at the bottom of the bottle and buoys up apencil, N, of carbon, so that it is pressed lightly against the carboncontact-surface F, attached to the diaphragm.- The carbon pen cil N isof the kind commonly used for electric lighting by incandescence. Theforce with which the carbon pencil N may be made to press against thecarbon button may be varied by raising or lowering the bottle K. Thecarbon pencil N is prevented from slipping from the surface of thecarbon button F by a short paper tube, I), slipped over the but ton andprojecting downward a short distance.

In Fig. 2 is shown acontact-surface consisting of a small roundedbutton, 0, of platinum, projecting from the end of a brass screw, d,upon which is placed a small vulcanite cup, 0. The brass screw 01 passesthrough the diaphragm and receives a nut, by which the vulcanite cup 0is drawn tightly against the diaphragm, and the screw is put intoelectrical connection with the diaphragm. The vulcanite cup serves tokeep the carbon pencil in the proper position relative to the platinumeontactsurface.

Either platinum or carbon may be used for the contact-surface; but myexperience has proven that platinum is to be preferred.

If a mica diaphragm be used in the instrument the communication betweenthe spring G and the cup E may be effected by attaching a strip ofcopper-foil to the surface of the diaphragm, where it will be pressed byboth cup and spring.

Themovable mercury-bottle presents an easy means of altering thepressure of the carbon pencil on the contact-surface attached to thediaphragm; but instead of this deviceI may place the mercury in a tubeand displace it, so as to vary the height, by means of a piston or screwentering the tube.

If it is desired to transmit sounds only, and not articulate speech, ametallic electrode may be used-instead of the carbon pencil N, or asmall electrode supported by a float of nonconducting material may beemployed.

In Fig. 3 a spring-lever, O, is secured to one side of thediaphragm-support, and extends across the diaphragm, and is providedwith an adj usting-screw, f. The free end of this lever WWI carries acarbon or platinum coiitactsurface, 9, like that already described inconnection with Figs. 1 and 2, and the surface is pressed by a floatingpencil, N, of carbon, as in the device hereinabove described.

This transmitter is placed in an electrical circuit, in which there is atelephone-receiver or the primary wire of an induction-coil, thesecondary wire ofwhich is in circuit with one or moretelephone-receivers. The current passes through the wire II, spring G,diaphragm 0, carbon button F, carbon pencil N, the men cury contained inthe bottle K, and the wire M, extending from the bottle through the baseof the instrument. Any sound made in the vicinity of this instrumentsets its diaphragm in vibration, and by moving the contact-surfacevaries the intensity of the current flowing through the electrodes. Bymeans of this instrument articulate speech may be clearly transmitted,and vocal and instrumental music may be sent over the line in a verysatisfactory manner.

To facilitate the collection of sounds I have attached to the cap I) ofthe diaphragm casc a flaring mouth-piece, which is curved, so that theSpeaker may occupy a natural position While using the instrument.

The chief advantages possessed by this instrument over others of itsclass are its extreme sensitiveness, it being capable of transmittingarticulate sounds made ten feet or ten inches from the instrument withequal facility. It can never get out of adjustment, as no springs,weights, or adjusting-screws are used or required, and for musical tonesit may be used both as transmitter and receiver.

Having thus described my invention, what lclaim as new, and desire tosecure by Letters Patent, is

1. In a transmitting-teleph0ne, a floating electrode, in combinationwith avibratory contact-surface, as herein specified.

2. In a transmitting-telephone, an adjustable mercury-receiver, afloating electrode, and a vibratory contact surface, in combination, asspecified.

3. In a transmitting-telcphone, a vibratory diaphragm carrying anelectrical contact-surface provided with a tubular carbon-pencil guide,in combination with the carbon pencil N and a buoying medium, asspecified.

4. The combination of the diaphragm 0, lever 0, contact-surface y, andfloating electrode N, as specified.

GEO. M. HOPKINS.

Witnesses II. M. llormxs, t. SEDGWICK.

